Method of forming shell roof structure



June 18, 1968 J. L. WALING METHOD OF FORMING SHELL ROOF STRUCTURE 3Sheets-Sheet 1 Filed Feb. 7, 1966 I N VEN TOR.

JasEPu L. WnLmq BY WM n TTORNEYS June 18, 1968 4. L. WALING 3,389,202

METHOD OF FORMING SHELL ROOF STRUCTURE Filed Feb. 7. 1966 3 Sheets-Sheetz .2 7. 5.. INVENTOR.

JOSEPH L Wm. m6

fl TTOPNEYS June 18, 1968 J. L. WALING METHOD OF FORMING SHELL ROOFSTRUCTURE 3 Sheets-Sheet 3 Filed Feb. 7, 1966 Q 5 Km m mm B m m UnitedStates Patent f 3,389,202 METHOD OF FORMING SHELL ROOF STRUCTURE JosephL. Waling, Lafayette, Ind., assignor to Purdue Research Foundation,Lafayette, Ind. Filed Feb. 7, 1966, Ser. No. 525,474 6 Claims. (Cl.264-134) This invention relates to the method of forming a shell roofstructure, that is a roof shell comprising a sheet of material buckledor formed to the desired shape and contour and being completelyself-supporting.

In carrying out the broad aspects of the invention, a large sheet ofsuitable bendable material, for example, foamed polystyrene, is laid outat the site. The sheet is cut to the desired outline and then by meansof suitable power operated equipment radially inward pressure is appliedto at least three circumferentially spaced points around the peripheryof the sheet and those points are pushed inwardly to thus buckle theremaining portions of the sheet upwardly to form a compoundly curvedsomewhat domed shell. As will be described, various means are employedfor rigidifying the shell in its final shape whereby the power machinerymay be withdrawn and the shell remains as a self-supporting roofstructure. The regions in which the pressure was applied become thelowermost or bearing portions of the shell and may be anchored tosuitable footings, pillars, or the like, depending upon the type offinished structure desired. Various means are disclosed for coating:and/or stifiening the sheet of material and for controlling thelocation and extent of the buckling thereof.

It is, therefore, a principal object of this invention to provide amethod of forming a self-supporting roof shell from bendable sheetmaterial, requiring no forms, molds, or the like.

Other and additional objects and advantages will become apparent tothose skilled in the art as the description proceeds with reference tothe accompanying drawings wherein:

FIG. 1 is a plan view of one representative adaptation of the invention,showing the power machinery in a schematic manner;

FIG. 2 is a perspective view of the shell resulting from the sheet ofFIG. 1;

FIG. 3 is a fragmentary enlarged sectional view taken on the line 33 ofFIG. 2;

FIG. 4 is a plan view of a different embodiment;

FIG. 5 is an edge elevational view of the form shown in FIG. 4;

FIG. 6 is a perspective view of the completed shell resulting from thematerial shown in FIGS. 4 and 5;

FIG. 7 is a plan view of a further modification employing a sheet ofdilferent shape;

FIG. 8 is an edge view of the sheet of FIG. 7;

FIG. 9 is a side view of the finished shell resulting from the shape ofFIG. 7;

FIG. 10 is a plan view of a still further embodiment showing analternative sheet outline;

FIG. 11 is a perspective View of a building constructed with the roofsheet of FIG. 10;

FIG. 12 is a plan view of a further alternative form wherein adifferently shaped sheet is employed and showing an alternative powerarrangement for buckling the sheet; and

FIG. 13 is a perspective view of the roof shell formed from the sheet ofFIG. 12.

Referring first to FIG. 1, numeral 2 represents :a large sheet ofmaterial from which the roof shell is to be formed and may comprise abuilt-up slab of formed polystyrene or the like. The slab is .arelatively large area and is preferably formed by cementing or adheringconven- 3,389,202 Patented June 18, 1968 "ice tional planks or slabs ofthe material in edge-to-edge relationship to define {a large unitarysheet which is cut to the desired outline. Such material is obtainablein plank form of varying thickness up to several inches.

In the form shown in FIG. 1, the outline of sheet 2 is generally squarebut wherein the sides are curved or :arced outwardly and the corners aretruncated as at 4 to define abutment surfaces. The sheet 2 is laid outin a generally horizontal plane and supported in a fiat condition in anysuitable manner, either directly on a supporting slab 6 or on a suitableframework to hold it elevated above the ground. A power mechanismcomprises an anchor arrangement 8 on which a plurality of sheaves 10 arejournalled. Below each of the truncated corners 4 a suitable guidingtrackway 12 is mounted and upon which a carriage 14 is slidably guided.Each carriage 14 includes a shoulder structure 16 abutting the truncatedcorner surface 4 of the sheet 2. A similar arrangement is provided ateach of the corners of the sheet 2 and from each carriage 14 a cable 18extends radially inwardly to and around one of the sheaves or pulleys10, then outwardly to a winch drum 20 driven by a suitable motor orengine 22. In the form shown, there is a slidable carriage 14 at eachcorner of the slab 2 and each carriage is connected by a cable 18 to thewinch 20. As will be obvious, operation of the motor or engine 22 tocause winch 20 to rotate will draw each of the cables 18 an equal amountand thus pull their respective carriages 14 inwardly toward the centerof the structure. This results in an upward buckling of the sheet 2 to acompoundly curved shape, such (as that shown in FIG. 2 of the drawings.Any bendable sheet material suitable for the practice of this inventionbecomes much stilfer and stronger when anchored in the buckled shapeshown and serves admirably as :a roof shell. After the sheet has beenbuckled upwardly, it is held in that position by securing the cornerportions 4 in any suitable manner to or on footings or pillars 24 (FIG.2). The power machinery comprising the trackways 12, carriages 14,anchor arrangement 8, and engine 22 and winch 20 may then be withdrawn.Suit able stifiening steps are performed to rigidity the sheet andrender it completely self-supporting and capable of withstanding theforces of nature.

The material employed for the shell may suitably be the foamedpolystyrene referred to but it may also comprise foamed polyurethene,foamed glass, Masonite, or other bendable materials or combinations andlaminations thereof.

Also, as will be obvious, the plate may be of fiat configuration and ofconstant thickness or on the other hand, the thickness of the plate orslab 2 may be varied from place to place to thus control its flexibilityand predetermine the shape of the finally buckled shell. In addition,different portions of the sheet 2 may be of different density or may beprovided with hollow portions and/0r fiat plate or spine-likeattachments to stifien certain portions thereof while leaving theremaining portions more flexible.

Obviously, the buckled shell must be rigidified to be usefullyself-sustaining and this may be accomplished in many ways. Afterbuckling, a coating of epoxy resins, fiberglass reinforced plastics orthe like may be applied to the inner or under surface of the shell andcaused to rigidify to thus render the shell sufiiciently stiif andstrong to support workmen for the application of an outer orweatherproofing coating. On the other hand, a layer 27 (FIG. 3) ofsettable resinous material, compatible with the sheet material 2 andcontaining fiberglass, asbestos, or other suitable reinforcing fiber,fabric, or mat, may be first applied to the upper surface of the sheet 2and the buckling of the sheet so timed that it is performed While thematerials 27 are still in a plastic state and so that those materials 27will solidify or set after buckling takes place. This upper stiffeninglayer coupled with a similar stiffening of the under surface, eitherduring or after buckling of the sheet 2, rigidifies the shellsutficiently to permit application of any desired additional materialsto the exterior and/ or the interior of the shell. The outer or weatherside of the shell may be finished as desired with additional layers ofreinforcements such as fiberglass strands or fabric, asbestos fibers ormat impregnated with epoxy, polyesters, or other plastics. Or it may befinished with reinforced concrete and an outer coating of waterproofingmaterial, if needed for the particular building. Or it may be finishedwith a thin skin of metal such as sheet aluminum or sheet steel glued tothe stiffened shell. The interior surface may be finished withadditional layers 26 of reinforced plastics, plaster, or otherarchitectural treatment.

FIGS. 4-6 illustrate another possible form wherein the starting sheet 32is of circular configuration. Before buckling the same, the legs orpillars 34 are secured thereto substantially in the manner illustratedin the drawings, to extend downwardly and outwardly from the edges ofthe sheet 12. The pressure-applying means would then be arranged toapply radially inward pressure to the outer ends of the legs 34 andsince the latter are rigidly connected to portions of the sheet 32, thelatter is caused to buckle while the legs 34 swing downwardly to agenerally vertical position. This is illustrated in FIG. 6 wherein thelegs 34 are shown secured to suitable footings or foundation members 36.FIG. 6 also shows the general shape assumed by the buckled shellresulting from the sheet of FIG. 4. FIGS. 7 through 9 show a generallytriangular sheet 38 having truncated corners 40 to which pressure isapplied to buckle the same to generally the shape shown in FIG. 9.

FIG. illustrates a further possible configuration for a sheet 42 whereintwo adjacent edges 44 are curved outwardly and two other adjacent edges46 are curved inwardly, there being four truncated corner portions 48,as shown. Obviously, buckling of the sheet 42 in the manner previouslydescribed will result in a shape similar to that indi cated in theperspective view of FIG. 11 wherein the inwardly curved edges 46 definethe edges of a carport or entry canopy '50. FIG. 11 also illustratesschematically how the walls of the building or the like 52 may beerected beneath the dome thus produced.

FIGS. 12 and 13 illustrate generally a square sheet of starting material54 having the previously described truncated corners 56. This figure,however, illustrates a modified form of power equipment wherein theguiding tracks 12 are provided at only two adjacent corners of the sheetand there are only two sliding carriages 14, one engaging each of theadjacent truncated corners. The

anchor device 58 is provided with only two pulleys 10 thereon to guidethe cables 18 attached to the two carriages 14. The other two truncatedcorners of the sheet 54 abut against fixed anchor blocks or abutments 60which are fixed in position and do not move. Obviously, upon operationof the motor or engine 22, the winch 20 will draw only the two cornersat the opposite side of the sheet inwardly and thus buckle the sheet ina different manner than it would if carriages were provided at all fourcorners. FIG. 13 illustrates generally the final buckled shell shaperesulting from the sheet shown in FIG. 12.

The described buckling may be produced by power means other than theengine and winch schematically shown herein, for example, hydraulicjacks, screw jacks. or other equipment may be temporarily attached toand activated against the foundations to exert the necessary pressure tothe edges of the sheet to produce the described buckling action.

As will be obvious, an infinite number of difierent shapes beyond thosealready described are possible and may be employed in combination withvarious distributions of buckling forces and to form a wide variety ofthin shell roof shapes.

The stiffened or rigidified shell is capable of supporting workmen andall expected loads without requiring shoring or other support.

While a limited number of specific shapes have been described and shownherein, and even though the method has been broadly described, it is tobe understood that the invention is not limited thereto but mayencompass other features and/or steps falling within the scope of theappended claims.

I claim:

1. The method of forming a shell structure from a bendable sheetmaterial, comprising the steps of: supporting a sheet of said materialin a generally horizontal plane; simultaneously applying pressureinwardly to at least three circumferentially spaced portions of theouter periphery of said sheet to thereby cause said portions to moveinwardly toward each other and said sheet to buckle to a compoundlycurved shape; and securing said portions, in their inner positions othold said sheet in said buckled shape.

2. The method set forth in claim 1 including the further step ofproviding stiffening material on said sheet to hold it in said buckledshape substantially independently of said securement of said portions.

3. The method of claim 2 wherein said further step is performed byapplying a layer of unhardened but hardenable material to at least oneface of said sheet before buckling the same and then holding said sheetin said buckled shape while causing said material to harden to asubstantially rigid state.

4. The method of claim 1 including the step of rigidly securing spacedsupport means to said spaced portions of said sheet to extend generallyoutwardly and downwardly therefrom, said radially inward pressure beingapplied to the outer ends of said support means whereby buckling of saidsheet causes said support means to extend generally vertically andthereby elevate said sheet and said spaced portions thereof above saidgenerally horizontal plane.

5. The method of claim 1 wherein said sheet is of substantially uniformcomposition and bendability throughout.

6. The method of claim 1 wherein preselected portions of said sheet arerendered stiffer than the remaining portions whereby to control thenature and extent of said bucklings.

References Cited UNITED STATES PATENTS boloid," in Architectural Record,July 1958, .pp. 191-195.

JAMES A. SEIDLECK, Primary Examiner.

.P. E. ANDERSON, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION atent No.3,389,202 June 18, 1968 Joseph L. Waling It is certified that errorappears in the above identified patent and that said Letters Patent arehereby corrected as shown below:

Column 1, line 70, "formed", second occurence, should read foamed Column3, line 24, "12" should read 32 Iolumn 4, line 24 "0t" should read toSigned and sealed this 20th day of January 1970.

SEAL) lttest:

Zdward M. Fletcher, Jr. JR.

Lttesting Officer Commissioner of Patents

1. THE METHOD OF FORMING A SHELL STRUCTURE FROM A BENDABLE SHEETMATERIAL, COMPRISING THE STEPS OF: SUPPORTING A SHEET OF SAID MATERIALIN A GENERALLY HORIZONTAL PLANE; SIMULTANEOUSLY APPLYING PRESSUREINWARDLY TO AT LEAST THREE CIRCUMFERENTAILLY SPACED PORTIONS OF THEOUTER PERIPHERY OF SAID SHEET TO THEREBY CAUSE SAID PORTIONS TO MOVEINWARDLY TOWARD EACH OTHER AND SAID SHEET TO BUCKLE TO A COMPOUNDLYCURVED SHAPED; AND SECURING SAID PORTIONS, IN THEIR INNER POSITIONS OTHOLD SAID SHEET IN SAID BUCKLED SHAPE.